03 April 2008
What turns you on? For the kakapo, New Zealand's giant flightless parrot, the answer may be key to its survival. Only 86 remain in the wild and the birds only breed every three to five years.
Hatchlings usually emerge at the start of a bumper season for the fruit they feed on. The eggs are incubated for 30 days, so the kakapo must lay them long before the fruit ripens. But what triggers them to mate and lay at the most opportune time has been a mystery.
Now Andrew Fidler of the Cawthron Institute in Nelson, New Zealand, and his colleagues may have the answer. According to their hypothesis, the unripened fruit of the rimu - a type of conifer that kakapo feed on - contains chemicals that mimic the action of the birds' sex hormones. Prior to a bumper crop, kakapo eat more unripened fruit than usual. The chemicals in it prime the liver so that come summer, when the lengthening days trigger the birds' ovaries to produce the sex hormone oestrogen, the liver responds by producing more egg-yolk protein, essential for developing eggs (Wildlife Research, vol 35, p 1).
The team suggest several approaches to testing the hypothesis. If it stands up, the chemicals in the unripened fruit could be used to increase the number of kakapo eggs laid, says Peter Sharp of the Roslin Institute in Midlothian, UK.
From issue 2650 of New Scientist magazine, 03 April 2008, page 14
* 01 June 2002
Two mates good for endangered parrots
* 28 May 2005
Kakapo recovery programme
Andrew Fidler, Cawthron